Gas springs are known from practice in a wide variety of embodiments. Many gas springs comprise an integrated valve system, whereby the gas spring can be fixed or locked infinitely variably in any position. In this case, the piston is sealed off at a pressure tube and separates two gas chambers from one another. When the valve is closed, the gas spring is arrested and allows locking in the desired position. By actuation of the trigger, usually embodied as a trigger tappet, the valve is opened and the gas spring can thus be positioned infinitely variably. The extending speed and damping can in this case be varied appropriately by choice of the nozzle in the piston.
Gas springs of the type in question here are used in a wide variety of ways. The use of such gas springs in office chairs is known from practice. Similarly, car seats or aircraft seats can be adjusted or parts of sunbeds can be moved by gas springs. Office desks can also be adjusted in height by gas springs.
The gas springs known from practice require an actuating element, which is operatively connected to an actuating device and acts directly on the trigger provided on the end side of the gas spring. In the case of office chairs, for example, this involves using actuating elements that take the form of simple levers which generally press directly on the trigger with an end-side region. Such a configuration of the actuating element has the great disadvantage that considerable forces are still required for triggering the gas spring. In addition to this there is the further disadvantage that it is only with difficulty that the triggering can be performed in stages, so that it is virtually impossible to regulate the speed of the gas spring under considerable triggering forces.
EP 0 907 842 B1 discloses a device for triggering a gas spring of the type mentioned at the beginning. Apart from the trigger lever, the actuating element of the known device also comprises two further levers, which are pivotably coupled to the trigger lever.
Furthermore, DE 197 16 720 A1 and EP 1 328 738 B1 disclose further devices for triggering a gas spring in which a lever mechanism is likewise used. In the case of the device known from DE 197 16 720 A1, there are two levers, which interact by way of a contact region. The operative connection between the levers is realized either by way of a toothing or by way of frictional surfaces lying against one another. The device according to EP 1 328 738 B1 is formed in such a way that the contact region and/or the actuating lever of the lever mechanism has a freely rotatable roller or ball for rolling on the actuating region and/or the contact region.